Combined logarithmic calculating device and writing implement



Sept. 7 1926. 1,599,102

J. SCHAUER COMBINED LOGARITHNIC CALCULATING DEVICE AND WRITING IMPLEMENT Filed March 23, 1926 Patented Sept. 7, 1926.

UNITED STATES 1,599,102 PATENT OFFICE.

JOACHIM SCHAUER, OF LWOW, POLAND.

COMBINED LOGARITHMIC CALCULATING DEVICE AND WRITING IMPLEMENT.

Application filed March 23, 1926, Serial No. 96,833, and in Germany December 31, 1924.

Attempts have already been made repeatedly to combine the logarithmic slide rule which is so frequently used with a writing implement. The inventions of this kind however proved cumbersome and unsuitable for use since they retained in the main the principle of the flat slide rule and merely consisted ,of adaptations of these in a cylindrical shape. The principal drawback which resulted from this was the covering up of the nib or pencil pointon each 'movement'of the slide in the direction of the said point so that the. writing down of the result of the calculation was only possible after the slide part had once more been pushed back.

This drawback of the slide rules combined with writing implements was-avoided by the present applicant in a previous invention forming the subject matter of German Patent No. 423,733 according to which a slide cylinder of half the length of the fixed scales was used. With this arrangement, however, the disadvantage arose that in many cases the length of the missing half of the scale on the slide had to be made up, for by corresponding movement of the slide which led to inaccuracies'and loss of time.

According to the present invention this drawback is eliminated bythe use of reciprocal logarithmic fixed scales and reciprocal logarithmic slide scale halves. By these .means it is rendered possible to execute every operation of multiplication and division of (two numbers by a single movement of the slide. In. the constructional form according to the invention hereinafter described, three factorsmay even in many cases be multiplied with one movement of the slide.

--This result which is unattainable with other types of combined slide rules and writing implements, represents not only a saving of time but also when the device is made up 1 A preferred constructional form of the' invention iscillustrated by way of example on the accompanying drawing in which:

Fig. l'is a cross section, Fig. 2 a plan, and Fig. 3 a longitudinal section of the combined slide rule and writing implement.

Referring to .Fig. 2 two complete logarithmic scales C and D are arranged parallel to one another on the outer surface of a pencil or fountain pen A. The scale C runs from left to right, the scale D from right to left and these two scales are arranged on the raised portion of the surface provided-with two gulde edges t and 2 (Fig. 1). Adjoining these guiding edges and runnin concentrically round the outer surface of t e writing implement is a slidable split cylinder B of half the length of the fixed scale. This split cylinder has on each of its two longitudinal edges one half of a complete lo \arithmic scale; the first of these two scales have their numbers running in I the same direction as those of the slide scales on the edges of the cylinder.

The device for pushing forward the lead half scales S (namely the upper one) carries holder is arranged at F. The slide cylinder is of elastic resilient material and can therefore be adjusted to any position.

The other usual scales, namely, the sine and tan ent scales, also the cube scaleand scaleof logarithms may be arranged on the remaining outer surface of the writing implement. Instead of these scales this space may also be used for special scales for various industrial purposes. In order that these scales should not be worn out by the slide cylinder the latter is folded over at its two longitudinal edges (Fig. The correlation of the extra scales with the fixed scale is effected by means of the cursor or by means of the ends ofthe slide cylinder.

The cursor consists of a short cylinder of glass or better still of any transparent unbreakable material fixed m a metal frame and is provided with a cursor line and with a spring a and a small metal'plate 1) (Figs. 1 and 3);

This upwardly pressing spring which is movable in a slot between the scales which is covered up except for a small medial slit by the outer covering of the fixed cylinder enables the cursor to be ad usted to any position and to remain always in a plane perpendicular to the axis of the cylinder owing to the action of the plate p. A cursor ring with a slightly curved surface of transparent material may also be used, said ring acting simultaneously as a lens. Finally the cursor ring may be con structed of transparent celluloid with a sharp edge for use as a cursor line.

In use the device is held between the thumb and forefinger of the left hand above the nib or pencil point. The slide cylinder and the cursor are moved with the right hand, after which the latter hand may be used to write down the result.

The multiplication of two numbers of which eachvhas a smaller numerical value 7 than 316 and of two numbers each of which v of the slide shown for given factors which lies side and toslide the scale division correcylinder under the cursor line.

\ places the scale extension and tiplied with a third factor.

has a greater numerical value'than 316 is effected by moving the slide divisions comprising these numbers along the correspond ing adjacent fixed scales G and D as on ordinary slide rules. These movements of the slide are only carried out from left to right since on account of the reciprocal scale the initial and final markings of the scale are opposite to one another.

In the case of two factors on which the one is smaller in numerical value than 316 and the other larger than 316, the method of scale extension is employed. One of the unit divisions of the slide is adjusted to the factor which lies nearer to the nib or pencil point i. e. to that one of the two factors which lies to the left; the division corresponding to the second factor on the opposite left half of the fixed scale shows the result on the adjacent slide scale.

In Fig. 2 of the drawing in the position example the product 1.4 .5:.7 will be found on the slide scale R underthe division 5 of the scale D. In the case of the multiplication of more than two factors this method is not advantageous as the result is not shown on the slide scale.

' In this case a method is used which consists in adjusting the cursor to that one of two on the right hand spondingtothe second factor on the slide The product is shown below the unit division of the slide on the same scale to which the cursor was adjusted.

This reciprocal method completely regives the prodit may be mul- In this way it is generally possible to find the product of three factors with one adjustment, the scale extension method being also used if necesuct on the fixed scale where sary.

V isfound on scale C under division nominator.

In Fig. 2 of the drawingthe position for the product 35 .4 2.-7::3.78 is shown. The division 4 of the scale R is set to the division 35 of the scale C by means of the cursor corresponding to GH; the product 14 on the lefthand side under S is not read off but instead of this the final product 27 of the scale S.

The division of two numbers can always be converted into a multiplication with the reciprocal of the divisor or denominator. This is effected by adjusting the cursor line or the end of the slide to the division corresponding to the divisor or denominator so that on the opposite scale the dividend or numerator of the factor appears and is dealt with as above described.

It is, however, generally more advantageous especially in three-fold calculations to effect operations of divisions by placing the denominator above the numerator or vice-versa on each of the two fixed scales:

If the scale division corresponding to the denominator on the slide is adjusted above that of the numerator, on the fixed scale, then the result is read as in the old slide rule under the unit division of the slide on the adjacent fixed scale.

If, however, the division corresponding to the denominator is taken on the fixed scale which is often necessary on account of the limited distance over which the slide is able to move then the quotient is readofi' under the opposite unit division on the opposite fixed scale.

In the position of the slide shown in Fig. 2 for example the division 15 of the scale S has been adjusted above thedivision 21 of the scale C to give the quotient of 1 the quotient 1.4 appears under the unit diserve; the result .71 appears on the scale D above the unit division of the slide scale R as the numerator was adjusted above the de- I claim:

1. A logarithmic calculating apparatus comprising in combination: a fixed scale member, a single logarithmic scale longitudinally arranged on said fixed scale member, a slide member sliding on said fixed scale member, a logarithmic half scale on said slide member. adjacent to and. co-operating with said single logarithmic scale and having its numbers running in the same direction as those of said single logarithmic scale, a second single logarithmic scale lonitudinally'arranged on said fixed scale memr, and a second logarithmic half scale on said slide member, said second single logarithmic scale and said second logarithmic half scale being adapted to co-operate with one another and having their numbers running in the opposite direction to those of said first-named single logarithmic scale and said first-named logarithmic half scale, substantially as described.

member guided longitudinally by the edgesof said raised portion, a logarithmic scale on said raised portion, a logarithmic half scale on said slide member co-operating with said'logarithmic scale and having its numbers running in the same direction as those of said logarithmic scale, a second logarithmic scale on said raised portion, a second half logarithmic scale on said slide member co-operating with said second logarithmic scale, the numbers of said second logarithmic scale and said second logarithmic half scale running in the opposite direction to those of the first named logarithmic scale and logarithmic half scale, and a cursor, substantially as described.

In testimony whereof I have hereunto set in hand.

y J OACHIM SCHAUER. 

